1. Field of the Invention:
This invention generally relates to a timer counting clock generator, and more particularly to such timer counting clock generator that is applied to a video tape recorder.
2. Description of the Prior Art:
In the apparatus where a tape is driven such as a video tape recorder, it is usually necessary to provide a function of detecting and displaying the residual amount of the tape or prevailing position thereof. Particularly, it is necessary to accurately detect and display the prevailing tape position in case of automatically editing video tape programs with a video tape recorder.
Hitherto, it has been the practice to detect the position of the tape being driven by a tape driving device by detecting the relative position of the tape through the counting of count pulses obtained from a counter roller rotated with the movement of the tape or by detecting the relative position of the tape by the counting of count pulses of a control signal recorded on the tape or by detecting the absolute address through reproduction of the SMPTE (the society of Motion Picture and Television Engineers) time code previously recorded on tape.
However, by the afore-mentioned detection method using a counter roller, slip exists between the video tape and roller, so that it is difficult to obtain a correct display of the tape position.
Also, by the method of counting the control signal, it is difficult to correctly detect the tape position due to the reduction of the output at the slow tape speed and signal drop out.
In particular, with the above prior art systems inaccurate counting is liable to result in case the direction of running the tape is changed a number of times.